Pressure-graduating device for talking-machine needles



H; w. MASON. PRESSURE GRADUAT'ING. DEVICE FOR T ALKiNG MA'CHINE NEEDLES.

APPLICATION F|LED MAY 5- 1919.

Patented Mar; 15, 1921;

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L 3543 I I UNITED STATES PATENT OFFICE.

PRESSURE-GRADUATING DEVICE FOR TALKING-MACHINE NEEDLES.

' tion.

This invention relates to certain new and useful improvements in a pressure graduating device for talking machine needles, and its principal object is to provide means for applying a variable lifting force to the sound box and its needle or stylus whereby the volume of the reproduced sounds may be controlled accordingly.

The invention consists of a spring tensioning device having connection with the sound box to tend to lift the same, and embodying means for varying the degree of tension of the spring device for governin the frictional contact between the need e and the playing record.

In the drawing Figure 1 is a fragmental side elevation of a tone arm, sound box and stylus of atalking machine embodying the present invention;

Fig. 2 is a cross-sectional view through tle 13pressure graduating device, on line 22 0 1g. 1;

Fig. 3 is a transverse section thereof on line 3-3 of Fig. 2; and

Fig. 4: is an elevation of a modified form of the invention.

Referring more in detail to the construction the numeral 1 designates the tone arm, 2 the sound box, and 3 the stylus or needle of a talking machine, the tone arm having its smaller end opening into a cross tube or T-fitting 4, which constitutes a bearing for the reduced end portion of the goose-neck or curved tubular arm 5 that directly carries the sound box. The reduced end portion of arm 5 extends the full length of the bearing 4 and has its outer end internally screwthreaded for engaging a plug disk 6 therein to close said tube. Encircling the adjacent end of the bearing 4 is a circular, strap clamp or bracket, 7 which has its ends connected by a tightening or clamping screw 8. A post or finger 9 is carried by the clamp 7 and extends from the bearing parallel with its axis.

A spring housing or casing 10 incloses the post and plug disk, having a central hub 11 Specification of Letters Patent.

Patented Mar. 15, 1921.

Application filed May 5, 1919. Serial No. 294,732.

seating on the disk and a circumferential flange 12 depending about the clamp 7. A flat coiled spring 13 is housed by the casing 10 and has one end anchored to the post and the other end to a post 14 on the hub 11. A threaded, axial opening 15, in the disk 6, receives the threaded portion of a clamping or adjusting screw 16, the latter passing through the hub and having its outer end provided with a head 17 which is rotated by gripping the knurled part 18 to advance and retract the screw.

The action of the spring is to exert a rotative force on the arm 5 and a lifting force action being varied by first loosening the screw 16, then rotating the casing to place the spring under more or less tension and finally tightening the screw which binds the hub against the plug disk. Should a light contact of the needle on the playing record be desired, the casing is rotated in the direction of the arrow in Fig. 1, to place the spring under greater tension, while for a firmer contact a reverse rotation of the easing is required, the screw 16 being tightened subsequent to each adjustment of the casing so is to fix the casing relative to the plug dis In the modified construction, a bracket 19 is clamped about the bearing 4 and equipped with a pivot pin or screw 20 to which is fulcrumed a leaf spring 21. One end of the spring extends beneath and supports the periphery of the sound box while the opposite end has a screw 22 threaded therethrough to bear on the face 23 of the bracket 19. By adjustment of the screw 22 the opposite end of the spring 21 may be caused to exert more or less tension against the sound box and thereby vary the playing contact of the needle on the record.

In either form the spring device is tensionable to a more or less degree, so that variation in the reproduced sound may readily be provided. The device is of simple construction and can readily be applied to the modern types of talking machines without material alteration.

at is claimed is:

1. In a talking machine, a tone arm having a transverse tubular bearing, a sound box, a tubular arm supporting the box and journaled in the bearing for swingingly mounting the same, a disk in'one end of the tubular arm, a bracket clamped about the ad- ,onthe sound box, the degree of this lifting j acent end of the bearing, a casing arranged eXteriorly of the disk and adjacent end of the bearing and inclosing the same, a coiled spring anchored at one end to the bracket and at the opposite end to the casing, and means for releasably securing the casing to the disk for Varying the tension of the riorly of the supporting arm mounting.

3. An attachment for talking machines, comprising, in combination, a support secured to the journaled end of the sound box supporting arm, a disk-like member mounted on said support and spaced from said end of the sound box supporting arm, a coiledspring secured at one end to said member and arranged in the space between the latter and the sound box supporting arm, and means securing the opposite end of the spring to the bearing for said arm.

4. In a talking machine, a tone arm having'a transverse tubular bearing, a sound box, a tubular arm supporting the'box and journaled in the bearingfor swingingly mounting the same," a disk in one end of the tubular arm, a bracket clamped about the adjacent end of the bearing and proyided with an outwardly extending post a casing inclosing the post and formed with a hub adapted to be clamped to the disk, a

coiled spring anchored at one end to the post and at the opposite end to the huband spaced from said end of the sound box supporting arm, a coiled spring secured at one end to said member and arranged in the space between the latter and the sound box supporting arm, and means se'curingthe op-.

posite'end of the spring to the bearing for said arm.

In testimony whereof I afiix mysignature. HENRY W. MASON.

Witness;

ROBERT A. TERRY. 

